The suspects are thought to be members of the Greek branch of the neo-Nazi Combat 18 group. Police said more residential searches are underway.

Combat 18 was a far-right group that began in Britain and later spread to other countries. The group's name is based on Adolf Hitler's initials -- the first and eighth letters of the alphabet.

Golden Dawn, a neo-Nazi party, remains the fourth largest in the Greek parliament.

A total of 70 Golden Dawn lawmakers and party officials are on trial on a wide range of charges, including membership of a criminal organization linked to the fatal stabbing of an anti-fascist rapper in 2013.

Far-right attacks have increased in Greece in recent months against leftwing activists and migrants.

In February, five people were injured after a group of eight people attacked an anti-fascist center in the Greek port of Piraeus.

The center was also attacked last August, and four people were arrested by the counter-terrorism unit in January.